Vacuum evaporation type water heater

ABSTRACT

The service water boiler has a conduit for the space heating system extending through it and downstream from the boiler the conduit is exposed to the steam in the vacuum heating tank which also houses that boiler. The space heating thermostat switch is in series with a switch operated by a sensor in the tank with the two being arranged so that the gas to the burner heating the tank is shut off when a given temperature is reached at said sensor. A second sensor in the tank will, at a temperature lower than the given temperature, actuate a second switch also connected to shut off the gas to the burner provided that the thermostat switch is not calling for heat.

United States Patent Altenstadt VACUUM EVAPORATION TYPE WATER HEATER Helmut Schmidt Auf- Altenstadt, Remscheid-Reinshagen. Germany Inventor:

Assignee: Jon. Vaillant KG, Remscheid, Berghauser,

Germany Filed: Oct. 19, I970 Appl. No.: 8|,728

Foreign Application Priority Data [451 May 9, 1972 [5 6] References Cited UNITED STATES PATENTS 2,348,6l0 5/l944 Colby ..237/l9 3,237,608 3/1966 Brandl 237/19 X 2,578,340 ll/195l De Lancey ..237/l9 X 57 ABSTRACT The service water boiler has a conduit for the space heating system extending through it and downstream from the boiler the conduit is exposed to the steam in the vacuum heating tank which also houses that boiler. The space heating thermostat switch is in series with a switch operated by a sensor in the tank with the two being arranged so that the gas to the burner heating the tank is shut off when a given temperature is reached at said sensor. A second sensor in the tank will, at a temperature lower than the given temperature, actuate a second switch also connected to shut off the gas to the burner provided that the thermostat switch is not calling for heat.

2 Claims, 1 Drawing Figure PATENTEDMAY 9 I972 HELMUT Sam/110T 620/" Aliens 146/2 IN V EN TOR BACKGROUND AND SUMMARY OF THE INVENTION The invention relates to a vacuum evaporation type water heater comprising an evacuated partly water-filled heated tank receiving a service water heating boiler and an independent heat exchanger of a circulatory space heating system. In water heaters of this kind it is known for the steam temperature in the tank to be adjusted by a temperature or pressure sensitive controller to a value above the required service water temperature, with the aim of ensuring that the flow temperature in the circulatory heating system is high enough. Unfortunately, this kind of steam temperature control leads to overheating of the service water boiler. It is, therefore, known for the return pipeof the circulatory heating system to be connected to a pipe coil in the boiler soas to cool the service water. The disadvantage of this arrangement, however, is that the service water is cooled only when the circulatory heating system is in operation; when such system ceases to operate, the service water is heated; excessively. It is an object of this invention to obviate this disadvantage and ensure that there is no overheating of the service water even when the circulatory heating system is not operating. According to the invention, therefore, the sensor of the controller has a second sensor connected in parallel with it which sensor is adjustable to a value corresponding to the'required service water temperature and which, upon cessation of operation of the circulatory heating system, automatically takes over the control of the steam temperature. Consequently, when the circulatory heating system is cut out of operation, the steam temperature is automatically reduced to a value appropriate for the service water temperature.

DESCRIPTION OF THE DRAWING The drawing illustrates, in diagrammatic form, an embodiment of the invention.

DESCRIPTION OF SPECIFIC EMBODIMENT The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvement. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

The illustrated embodiment includes an evacuated receptacle or tank 1 having a heat-insulating covering 2. Tank 1 contains a relatively small amount of water 3 and when heated by a heat source 4 the water turns into steam. Disposed in the steam chamber 5 of tank I are a service water boiler 6 and a heat exchanger 7. Heat exchanger 7 is a part of a circulatory space heating system represented by a radiator 8 and a circulating pump 9. Boiler 6 is connected to a cold water intake pipe 10 and to a draw (discharge) pipe 11.

A flow pipe 12 extends from heat exchanger 7 to the radiator 8. A return pipe or conduit 13 extends back to the heat exchanger 7 and includes pump 9 and a pipe coil 14 in the boiler 6. Consequently, the water returning through line 13 is, when in pipe coil 14, in heat exchange relationship with the service water contained in boiler 6.

Disposed in chamber 5 is a sensor 15 (responsive either to temperature or to pressure) which, when a preset steam temperature is exceeded, opens a switch 16. A switch 19 which could be a room thermostat or some other master switch for controlling the circulatory heating is in series with switch 16. Switch 16 is disposed in the circuit of a solenoid valve 17 to energize the solenoid and open the gas line when the switch 16 closes (provided thermostat switch 19 is closed). If the room then'nostat continues to call for heat but the temperature in chamber 5 reaches a preselected maximum (e. 105 C.) switch 16 opens to close the gas valve by braking t e electrical circuit to the solenoid. Also disposed in chamber 5 is a second sensor 20 which operates at a lower steam temperature than that of sensor 15 (e.g. 90 C. At this temperature sensor 20 opens a switch 21 which is closed below the selected lower temperature. Switch 21 is in parallel with the series circuit of switch 16 and room thermostat 19.

In normal heating operation, the sensor 15 and switch 16 are responsible for controlling the steam temperature in chamber 5 to 105 C. Since the return water from the circulatory heating system is flowing through pipe coil 14, the service water in boiler 6 is cooled and does not overheat. So long as switches 16 and 19 are closed, the opening of switch 21 has no effect. However, when the circulatory heating system is cut out of operation either by the open switch 19, room thermostat, or because the complete system is running in summer conditions, sensor 20 and switch 21 take over the control of the steam temperature in the chamber 5 at a lower value, e. g. 90 C. Thereby, the absence of cooling of boiler 6 by the return water from the circulatory heating system does not cause the temperature of the water in the boiler to become excessive.

Instead of two sensors 15, 20 being used, just a single sensor can, of course, be used; the single sensor can, in known manner, be adjusted to operate switches at two different temperature (or pressure) levels, the lower level being the level used when the circulatory heating system is inoperative. The steam temperature can be controlled by temperature-sensitive devices (thermostats) and by sensors responsive to steam pressure.

I claim:

I. In a heating system comprising an evacuated partially water-filled tank, a service water boiler in the tank, a space heating system return conduit extending through the boiler, a gas burner line, a solenoid valve in said line and having an operator for controlling the valve, and control means connected to the operator for opening and closing the valve, said control means including a master control, sensor means in said tank and responsive to the pressure/temperature conditions in the tank and primary sensor switch means, said control means opening the valve when said master control calls for heat and said sensor means detects that the pressure/temperature conditions are below a preselected amount and closing said valve when said preselected pressure/temperature conditions are exceeded, the improvement wherein said control means includes:

second sensor switch means connected to the sensor means for operating said valve for closing said valve when a given temperature lower than said preselected temperature is exceeded provided that the master control and primary means is not calling for heat, said valve having a solenoid, said control means including a series electrical circuit through said solenoid, said master control and said primary sensor switch means, said second sensor switch means being in parallel with that part of said circuit consisting of the master control and the primary sensor switch means.

2. In a system as set forth in claim 1, wherein said sensor means comprises two separate sensors, each of which actuate a respective sensor switch. 

1. In a heating system comprising an evacuated partially waterfilled tank, a service water boiler in the tank, a space heating system return conduit extending through the boiler, a gas burner line, a solenoid valve in said line and having an operator for controlling the valve, and control means connected to the operator for opening and closing the valve, said control means including a master control, sensor means in said tank and responsive to the pressure/temperature conditions in the tank and primary sensor switch means, said control means opening the valve when said master control calls for heat and said sensor means detects that the pressure/temperature conditions are below a preselected amount and closing said valve when said preselected pressure/temperature conditions are exceeded, the improvement wherein said control means includes: second sensor switch means connected to the sensor means for operating said valve for closing said valve when a given temperature lower than said preselected temperature is exceeded providEd that the master control and primary means is not calling for heat, said valve having a solenoid, said control means including a series electrical circuit through said solenoid, said master control and said primary sensor switch means, said second sensor switch means being in parallel with that part of said circuit consisting of the master control and the primary sensor switch means.
 2. In a system as set forth in claim 1, wherein said sensor means comprises two separate sensors, each of which actuate a respective sensor switch. 